Properties Of Mn-doped ZnO Nanoparticles Research Articles

Structure, microstructure, and ESR properties of concentration-dependent Zn1-xMnxO nanoparticles

In this study, the estimated stress, strain, and crystallite sizes of different Mn-doped ZnO nanoparticles were calculated using the Williamson-Hall method and compared with the values obtained from the Debye-Scherrer formula. Moreover, defects, and magnetic properties of Mn-doped ZnO nanoparticles at different concentrations were investigated. The sol-gel method was used to synthesize nanoparticles. The X-ray diffraction and Rietveld analysis results confirm that the desired structure is formed and that no secondary phase is present up to an Mn concentration of x=0.2. In and out of plane lattice parameters, cell volumes, bond length, atomic locality, and dislocation density (δ) were clarified. The grain size of the concentration-dependent samples was provided by scanning electron microscope. Photoluminescence (PL) spectra exhibited ultraviolet emission along with a broad band encompassing violet, blue, and red regions, attributed to defect-related and excitonic emissions. These emissions were notably influenced by synthesis conditions and doping elements and ratios. Electron spin resonance properties of the concentration-dependent samples were analyzed to figure out the g-factor through line widths of pike-to-pike (ΔHPP) of ESR spectra. Mn-doped ZnO nanoparticles exhibited ferromagnetism at room temperature.

Structure, microstructure, optical and photocatalytic properties of Mn-doped ZnO nanoparticles

In this work, Zn1−xMnxO samples were synthesized by the hydrothermal method by varying the dopant ratio from x = 0.01 to 0.05 with 0.01 increment. Structural, optical and photocatalytic properties of Mn-doped ZnO were analyzed based on their concentration dependence. Structural behavior of the nanoparticles was studied by X-ray diffraction technique and it was found that Zn1−xMnxO samples were hexagonal Wurtzite structure with no secondary phase. The effect of Mn element in Zn1-xMnxO composition was clarified by calculating lattice parameters, cell volumes, stress, microstrain, the locality of the atoms dislocation density, displacement of atoms and bond length. SEM images revealed random agglomeration. The band gap and Urbach energies of Zn1−xMnxO structures were determined and discussed. Different models were used to calculate refractive index and the refractive index was found in the range of 2.05–2.72. Mn-doped ZnO nanoparticles exhibited lower degradation rate constants (k = 0.0004–0.0009 min−1) than that of pure ZnO (k = 0.0014 min−1). Doping Mn increased the Urbach energy value.

Synthesis, Characterization, Photocatalytic and Sensing Properties of Mn-Doped ZnO Nanoparticles.

In this paper, Mn-doped ZnO nanoparticles (0 to 10 mol% Mn) were synthesized by facile low-temperature aqueous solution process and characterized by several techniques such as field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-visible and Raman-scattering spectroscopy. The SEM studies confirmed that the synthesized nanoparticles are grown in high density and increase in Mn content was found to have a significant effect on the morphologies of ZnO nanoparticles. The XPS studies established the structural variation of the samples with the change in dopant concentration and its oxidation state. XPS probe the existence of impurity phases in the as-synthesized samples. The results indicate further that hexagonal wurtzite structure of ZnO undergoes distortion with the increase in the dopant concentration. Also, with the increase in the dopant concentration, the blue-shift was observed in the UV-vis. spectra. Photocatalytic and chemicals sensing performances of these nanomaterials have been investigated by subjecting them to photocatalytic degradation of methyl orange (MO) under UV irradiation and for the detection of picric acid (PA) in aqueous solutions. Mn doped ZnO samples were found to be more efficient in catalyzing the MO degradation than pure ZnO. 5 mol% Mn doped ZnO nanomaterials were studied to use as fluorescence sensor for the detection of PA and the observed detection limit was found to be 2.5 μM.

Structural, Optical, and Magnetic Properties of Mn-doped ZnO Nanoparticles Synthesized by Coprecipitation Method

Many studies have been conducted to produce ZnO including in the form of powder and film. This paper reports the characteristics of structures, optics, and magnetics of Zn1-xMnxO nanoparticles synthesized by coprecipitation method. The range of x value was maintained in the range of 0 to 0.03. The X-RD data analysis showed that all samples formed in nanosized. The lattice parameters sifted for all x values indicating the Mn ion was inserted into ZnO replacing Zn ion. The optical properties presented that the increase of Mn ion decreased the gap energy nanoparticles. Furthermore, the addition of Mn ion in the samples resulted in different magnetic properties.

Synthesis, characterization and properties of Mn-doped ZnO nanoparticles

In the present study, undoped and Mn-doped ZnO nanoparticles with different Mn concentrations (4 and 6 at.%) have been prepared by polymeric precursor method. The effects of Mn content on the structural, optical, and magnetic properties of these nanoparticles were investigated in detail. Room temperature X-ray diffraction (XRD) data revealed hexagonal wurtzite structure of the samples and no other secondary phase has been noticed. The microstructural analysis confirms that the particles of Mn:ZnO are spherical in shape with size ranging between 32 and 45 nm as calculated by Scherrer’s equation and transmission electron microscopy (TEM) images. UV–visible absorption spectroscopy measurements affirm a blue-shift in the band gap with increasing Mn doping in ZnO. The hysteresis loops (M–H) exhibit ferromagnetic behaviour of all samples at room temperature. Temperature-dependent resistivity measurements show semiconducting nature of the samples and reduction in the resistivity on Mn substitution.

Protic Ionic Liquid Assisted Synthesis, Structural, Optical and Magnetic Properties of Mn-Doped ZnO Nanoparticles

Protic Ionic Liquid Assisted Synthesis, Structural, Optical and Magnetic Properties of Mn-Doped ZnO Nanoparticles

Correlation between structural, optical and magnetic properties of Mn-doped ZnO

We have investigated the structural, optical and magnetic properties of Mn-doped ZnO nanoparticles with different doping concentrations (0, 2, 4 and 6 %) synthesised by sol–gel method. Lattice parameters, cell volume, atomic packing fraction, crystallite size and confirmation of hexagonal wurtzite crystal structure have been studied by X-ray diffraction data. Surface morphology as well as grain size and the presence of all the elements have been confirmed by scanning electron microscope and energy-dispersive X-ray spectroscopy, respectively. The decrease in lattice parameters ratio (c/a) with Mn concentration indicates lattice distortion with the incorporation of Mn2+ ions at Zn2+ site of ZnO structure, which has been confirmed by Raman analysis. It has been observed that microstructure defects induced some extra Raman vibration modes. Ultraviolet–visible analysis shows that absorption edge lies in visible region, and encroachment in visible region increases, while energy band gap decreases with the increase in Mn concentrations. We have recorded FTIR spectra at room temperature to study the vibrational bands present in Zn1−x Mn x O samples. The magnetic study of samples indicates ferromagnetic behaviour at room temperature. The magnetic properties increases with doping concentration due to small lattice distortion and defects.

Mn-Doping Effects on Structure and Magnetic Properties of ZnO Nanoparticles

Magnetic properties of Mn-doped ZnO nanoparticles, synthesized by the co-precipitation method, have been studied. The presence of a single crystalline phase identified as the wurtzite structure was determined by X-ray diffraction measurements in all the samples. Additional Bragg reflections associated to manganese oxides phases have been found in the 10 mol\(\%\) Mn-doped ZnO sample which are more evident after calcinating at high temperatures. Magnetization measurements reveal a paramagnetic behavior with antiferromagnetic interactions becoming weaker as the Mn concentration is increased. For the 10 mol\(\%\) Mn-doped ZnO sample the coexistence of a paramagnetic and a ferromagnetic phase has been determined. The latter phase was associated with the presence of Mn\(_3\)O\(_4\) compound which is in agreement with the structural results.

Correlation between the structural and optical properties of Mn-doped ZnO nanoparticles

The crystallographic and optical properties of Mn-doped ZnO nanoparticles prepared by a sol–gel process have been investigated by X-ray diffraction, UV-visible absorption spectroscopy and cathodoluminescence microanalysis. X-ray diffraction reveals that the nanoparticles have hexagonal wurtzite crystal structure, with the lattice constants along the a- and c-axes increasing with increasing Mn concentration from 0 to 2.4at%. For all Mn concentrations in this range, the nanoparticles are essentially free of native point defects so that they exhibit only band-edge luminescence. The optical bandgap and band-edge emission energies for Mn-doped ZnO were found to increase in proportion to the lattice constants. The direct correlation between the bandgap and crystal structure suggests that the band-edge optical properties of Mn-doped ZnO is predominantly influenced by the amount of Mn atoms substituting Zn on the lattice sites.

Synthesis, structure and ferromagnetic properties of Mn-doped ZnO nanoparticles

Nanosized Mn-doped ZnO particles were synthesized by a rheological phase reactionprecursor method and the thermal decomposition of the oxalate precursors was studied bythermogravimetry and differential thermal analysis in air atmosphere. X-ray analysisreveals that the Mn-doped ZnO crystallizes in a wurtzite structure. The lattice constants ofZn1−xMnxO increase slightly when Mn is doped into ZnO. TEM analysis shows that the average diameterof the nanoparticles is about 10–13 nm. In addition, magnetization measurements underfield cooling conditions reveal that the Mn-doped ZnO nanoparticles show ferromagneticbehaviour at room temperature and both the susceptibility and coercive force ofZn0.95Mn0.05O are largerthan those of Zn0.97Mn0.03 and Zn0.93Mn0.07. This work demonstrates that Mn can be doped into nanosized ZnO by the method ofrheological phase reaction, which represents an important method to synthesize a nanosizeddiluted magnetic semiconductor.

Structure and magnetic properties of Mn-doped ZnO nanoparticles

We report the crystal structure and magnetic properties of the Zn1−xMnxO compounds synthesized by a combustion method. The Zn1−xMnxO compounds with x=0–0.1 crystallize in the wurtzite ZnO structure. The lattice parameters a and c of Zn1−xMnxO increase linearly with the Mn content, indicating that Mn2+ ions substitute for Zn2+ ions. Scanning electron microscopy shows that the average particle radius of Zn0.95Mn0.05O is about 40 nm. From the Curie–Weiss behavior of susceptibility at high temperature, it was found that the Mn–Mn interaction is dominated by antiferromagnetic coupling with effective nearest-neighbor exchange constant J about −32 K and the large negative value of the Curie–Weiss temperature.